Company delaying relieving letter

Dear People, I had been working with a company which acts as a vendor to MNC in corporate training. I had been working with this company for past 1.5 years. The pay was inline with offer later in the initial months but later it has been said that TDS has to be applied even though the offer letter says the salary is after all deductions. So TDS was deducted in later months as arrears and while discussing about this with reporting manager the discussion ended with harsh words and the manager has instructed to report to office for getting relieved . I completed the relievung procedures from my side while the company has delayed the relieving letter issuance and crediting if salary for past 3 months. I have an offer with me already and the new employer makes the relieving letter mandatory. I had dropped mail several times to the past employer about the relieving letter and pending salary credit. But still the employer doesn’t reply and stated in one mail that it can take up to 60 working days. This seems to be intentional to delay the process. I had sent a registered post about this concern but no reply . Kindly guide with further steps in this .